The photochemical conversion of reactants having a reactant core portion of 5,7-androstadiene-1.alpha.,3.beta.-diol, into a product having an altered product core portion, 9,10-seco-5(10),6,8-androstatriene-1.alpha.,3.beta.-diol, is known. Furthermore, it is known that this reaction proceeds most efficiently when the irradiating light is restricted to being in the range from about 275 or 280 nm (nanometers) to about 310 nm. Such is discussed, for example, by Sato, et al, J. Nutr. Sci. Vitaminol. 26, 545-556, 1980; in Sato, et al Chem. Pharm. Bull. 26 (10) 2933-2940 (1978); and Barton, et al, J. Am. Chem. Soc. 95, 2748-2749 (1973). Unfortunately, relatively low yields, of the order of 15 to 40%, of 1.alpha.-hydroxyprevitamin D.sub.3 are producible by the prior art methods. And, such methods have normally produced relatively great amounts of undesirable byproducts through decomposition of materials in the reaction mixture.
A method of producing 1.alpha.-hydroxyprevitamin D.sub.3 in better yields and with less destruction of valuable starting 1.alpha.-hydroxyprovitamin D.sub.3, and of producing related compounds, would be highly desirable.
The present invention is directed to overcoming one or more of the problems as set forth above.